The present invention relates generally to self-propelled construction equipment and, more particularly, to a self-propelled construction vehicle having a steerable transport assembly which is selectively adjustable for operation of the vehicle in two transverse, preferably perpendicular, transport directions.
Self-propelled construction vehicles and other construction equipment of diverse types are well known. One type of such construction equipment are so-called slip-form paving machines essentially adapted to continuously form concrete or another flowable paving material along the ground or other base surface, for example, to form a roadway. Diverse forms of such machines have been described in prior patents, representative examples of which may be found in U.S. Pat. Nos. 3,175,478; 3,264,958; 3,637,026; 3,771,892; 3,970,405; 4,197,032; 4,360,293; 4,925,340; 4,948,292; 5,044,820; and 5,590,977.
Conventionally, it is commonplace for paving equipment of this type to support the machine frame on a plurality of so-called crawler track assemblies, typically four such assemblies mounted in laterally and longitudinally spaced relation to one another at four corners of the machine frame, with each assembly having an endless ground-engaging self-propelled track supported by an associated steering mechanism for pivotable steering movement about a vertical steering axis which thereby facilitates steerable driving of the paving machine over substantially any ground surface along which a roadway is to be paved. The frame of the machine supported by the crawler assemblies may have various devices and mechanisms to perform various functions, including a substantially horizontally disposed undersurface, commonly referred to as a screed, for purposes of leveling and finishing concrete material. In basic operation, a continuous supply of concrete or other suitable paving material is deposited in front of the paving machine between its laterally spaced crawler assemblies as the machine is driven over the intended path of the roadway, whereby the concrete material is spread, leveled and finished by the screed.
In some currently conventional machines, the crawler assemblies may be movable between a forwardly oriented (i.e. front-to-back) xe2x80x9chomexe2x80x9d position, while being steerable within a designated range from the home position, for driving the machine forwardly relative to the longitudinal extent of the frame, and a laterally oriented (i.e. side-to-side) xe2x80x9chomexe2x80x9d position, while also being steerable within a designated range from the home position, for driving the paving machine laterally, which optimally facilitates driving transport and movement of the machine from one location to another. Such movability in the xe2x80x9chomexe2x80x9d orientation of the crawler assemblies is particularly beneficial in larger paving equipment, such as equipment wherein the lateral spacing between the crawler assemblies is set so as to facilitate the paving simultaneously of two lanes of roadway side-by-side. Because of the substantial width of machines of this size, they cannot always be driven in a forward direction. For example, for purposes of transport from one location to another, such machines must be of a longitudinal front-to-back dimension which can be supported on a conventional flat-bed truck for transport over public highways and roads. Hence, such machines must be drivable in a lateral direction for loading onto and off of a transport trailer.
Some prior paving machines have steerable crawler assemblies equipped to be adjustably switchable between forward and lateral xe2x80x9chomexe2x80x9d steering positions, but the mechanical arrangement for switching from one home position to the other home position is disadvantageously complicated and time consuming to accomplish. Steering of the crawler assemblies in such machines is commonly accomplished via a hydraulic piston-and-cylinder assembly extending from the machine frame to the crawler assembly for actuating pivoting movements of the crawler assembly about the vertical steering axis. In order to switch each crawler assembly from one home position to the other home position, the connection between the steering piston-and-cylinder assembly is operated to turn the crawler assembly about ninety (90) degrees into the new home position, and then the piston-and-cylinder assembly is disconnected and re-connected to a different mounting location on the crawler assembly. In conventional practice, this operation is time consuming and labor intensive to accomplish, even assuming no difficulty in aligning the steering piston-and-cylinder assembly with the crawler assembly for reconnection, and then the adjustment operation must be re-performed once the machine has been moved to a new position or a new paving location.
Other paving machines are known which have steerable crawler assemblies which may be moved between forward and lateral xe2x80x9chomexe2x80x9d steering positions without the necessity of disconnecting and reconnecting any components of the steering arrangement. One such paving machine is disclosed in U.S. Pat. No. 5,590,977, wherein the steering arrangement is capable of moving the crawler assemblies through a range of motion greater than ninety (90) degrees without any reconfiguration of the steering arrangement. Disadvantageously, however, in order for the steering arrangement to have a desirable range of steering motion in the forward xe2x80x9chomexe2x80x9d position, yet still be movable approximately ninety (90) degrees into a lateral xe2x80x9chomexe2x80x9d position, the mechanical limitations of the steering arrangement enable only a much more limited range of steering motion with the crawler assemblies in the lateral xe2x80x9chomexe2x80x9d position which limits the usefulness and maneuverability of the machine in transverse steering operation. Other known conventional paving machines utilize a structure supporting the steered crawler assemblies commonly referred to as a xe2x80x9cswinging legxe2x80x9d arrangement which rotates about a pin at the main frame of the machine. Such steering arrangements also are capable of moving the crawler assemblies through a range of motion greater than ninety (90) degrees so as to be capable of orienting the crawler assemblies in both forward and lateral xe2x80x9chomexe2x80x9d positions with a reasonable range of steering motion in each such position. However, upon switching between differing xe2x80x9chomexe2x80x9d positions, the steering and propulsion hydraulic systems for the paving machine must be modified to allow proper operation in the new direction of travel, all of which tends to be very time consuming to accomplish.
Accordingly, it would be highly desirable to provide a more automated, simplified and streamlined means for easily switching a crawler assembly from one xe2x80x9chomexe2x80x9d steering position to another, so as to improve the efficiency and usefulness of the machine.
It is accordingly an object of the present invention to provide an improved mechanical arrangement for changing a crawler assembly or other form of transport assembly, such as on a self-propelled construction vehicle, from one xe2x80x9chomexe2x80x9d steering position to another, which can be performed much more easily and quickly than with the conventional adjusting means described above and which otherwise overcomes the disadvantages of the known conventional arrangement.
Briefly summarized, the present invention is basically applicable to any self-propelled construction or like vehicle having a frame supported on a steerable transport assembly comprising a ground-engaging structure, such as an endless track crawler assembly, depending from a steering mechanism moveable within a defined range of steering relative to a generally vertical steering axis. The steering mechanism will typically comprise an upstanding post integrally coupled to the ground engaging structure for unitary rotation thereof about the steering axis and a steering control assembly comprising a collar assembly coupled to the post and an actuator mounted to the frame and coupled to the collar assembly for driving rotation of the collar assembly and the post selectively in opposite rotational directions.
In accordance with the present invention, the collar assembly basically comprises a driving collar element integrally coupled to the actuator and a driven collar element integrally coupled to the post. The driven collar element is affixable to the driving collar element selectively in a first disposition relative to the driving collar element for orienting the post and the ground engaging structure for steering the vehicle in a first transport direction and in a second disposition relative to the driving collar element for orienting the post and the ground engaging structure angularly spaced from the first disposition for steering the vehicle in a second transport direction.
In a preferred embodiment, the driving and driven collar elements are disposed for relative rotation about the steering axis between the first and second dispositions when not affixed to one another. More specifically, the driving collar element preferably is disposed annually about the driven collar element for relative rotation therebetween. The driving collar preferably has two coupling locations angularly spaced from one another and the driven collar element has a coupling location adapted for affixation selectively to either of the coupling locations of the driving collar element. The actuator preferably is operable in each of the first and second dispositions of the collar elements for driving rotation of the collar assembly within a defined range for steering of the vehicle in a selected one of the transport directions. The upstanding post preferably is extendable for selectively controlling elevation of the ground engaging structure relative to the frame. Typically, the vehicle will comprise a plurality of the steerable transport assemblies, e.g. four such assemblies spaced laterally and longitudinally with respect to one another, and a steering control system for coordinated movement of the transport assemblies.
The present invention is particularly adapted for use in a construction vehicle of the type configured for slip-forming a paving material along a ground surface, e.g., a roadway, as the vehicle is steered in a selected one of the transport directions.
Other details, features and advantages of the invention will be described and understood from a description of a preferred embodiment of the invention set forth below with reference to the accompanying drawings.